Metrical patterns of the Tang poetry

The main achievements of the Tang poetry are ancient poems, quatrains, and regulated poems. The Tang poetry is best represented in the High Tang, when it reached the peak. However, the main achievement of the High Tang poetry is not in regulated poetry. It was very casual in quatrains, but since the Tang Dynasty the law of level and oblique tones has been used to make poetry more smooth. It was not until the Tang Dynasty that it became fully mature; thus, as in modern poetry, it naturally had the features of regular level and oblique tones and antithesis, which are considered a free use of the characteristic of poetic language rather than a metrical form. Generally speaking, poets good at writing seven-character ancient poetry tend to be unconstrained in personality because it is especially suitable for poets to experiment and develop their vigorous imagination.